Vegard Nossum | dfec072 | 2008-04-04 00:51:41 +0200 | [diff] [blame^] | 1 | #include <linux/interrupt.h> |
| 2 | #include <linux/kdebug.h> |
| 3 | #include <linux/kmemcheck.h> |
| 4 | #include <linux/kernel.h> |
| 5 | #include <linux/types.h> |
| 6 | #include <linux/ptrace.h> |
| 7 | #include <linux/stacktrace.h> |
| 8 | #include <linux/string.h> |
| 9 | |
| 10 | #include "error.h" |
| 11 | #include "shadow.h" |
| 12 | |
| 13 | enum kmemcheck_error_type { |
| 14 | KMEMCHECK_ERROR_INVALID_ACCESS, |
| 15 | KMEMCHECK_ERROR_BUG, |
| 16 | }; |
| 17 | |
| 18 | #define SHADOW_COPY_SIZE (1 << CONFIG_KMEMCHECK_SHADOW_COPY_SHIFT) |
| 19 | |
| 20 | struct kmemcheck_error { |
| 21 | enum kmemcheck_error_type type; |
| 22 | |
| 23 | union { |
| 24 | /* KMEMCHECK_ERROR_INVALID_ACCESS */ |
| 25 | struct { |
| 26 | /* Kind of access that caused the error */ |
| 27 | enum kmemcheck_shadow state; |
| 28 | /* Address and size of the erroneous read */ |
| 29 | unsigned long address; |
| 30 | unsigned int size; |
| 31 | }; |
| 32 | }; |
| 33 | |
| 34 | struct pt_regs regs; |
| 35 | struct stack_trace trace; |
| 36 | unsigned long trace_entries[32]; |
| 37 | |
| 38 | /* We compress it to a char. */ |
| 39 | unsigned char shadow_copy[SHADOW_COPY_SIZE]; |
| 40 | unsigned char memory_copy[SHADOW_COPY_SIZE]; |
| 41 | }; |
| 42 | |
| 43 | /* |
| 44 | * Create a ring queue of errors to output. We can't call printk() directly |
| 45 | * from the kmemcheck traps, since this may call the console drivers and |
| 46 | * result in a recursive fault. |
| 47 | */ |
| 48 | static struct kmemcheck_error error_fifo[CONFIG_KMEMCHECK_QUEUE_SIZE]; |
| 49 | static unsigned int error_count; |
| 50 | static unsigned int error_rd; |
| 51 | static unsigned int error_wr; |
| 52 | static unsigned int error_missed_count; |
| 53 | |
| 54 | static struct kmemcheck_error *error_next_wr(void) |
| 55 | { |
| 56 | struct kmemcheck_error *e; |
| 57 | |
| 58 | if (error_count == ARRAY_SIZE(error_fifo)) { |
| 59 | ++error_missed_count; |
| 60 | return NULL; |
| 61 | } |
| 62 | |
| 63 | e = &error_fifo[error_wr]; |
| 64 | if (++error_wr == ARRAY_SIZE(error_fifo)) |
| 65 | error_wr = 0; |
| 66 | ++error_count; |
| 67 | return e; |
| 68 | } |
| 69 | |
| 70 | static struct kmemcheck_error *error_next_rd(void) |
| 71 | { |
| 72 | struct kmemcheck_error *e; |
| 73 | |
| 74 | if (error_count == 0) |
| 75 | return NULL; |
| 76 | |
| 77 | e = &error_fifo[error_rd]; |
| 78 | if (++error_rd == ARRAY_SIZE(error_fifo)) |
| 79 | error_rd = 0; |
| 80 | --error_count; |
| 81 | return e; |
| 82 | } |
| 83 | |
| 84 | static void do_wakeup(unsigned long); |
| 85 | static DECLARE_TASKLET(kmemcheck_tasklet, &do_wakeup, 0); |
| 86 | |
| 87 | /* |
| 88 | * Save the context of an error report. |
| 89 | */ |
| 90 | void kmemcheck_error_save(enum kmemcheck_shadow state, |
| 91 | unsigned long address, unsigned int size, struct pt_regs *regs) |
| 92 | { |
| 93 | static unsigned long prev_ip; |
| 94 | |
| 95 | struct kmemcheck_error *e; |
| 96 | void *shadow_copy; |
| 97 | void *memory_copy; |
| 98 | |
| 99 | /* Don't report several adjacent errors from the same EIP. */ |
| 100 | if (regs->ip == prev_ip) |
| 101 | return; |
| 102 | prev_ip = regs->ip; |
| 103 | |
| 104 | e = error_next_wr(); |
| 105 | if (!e) |
| 106 | return; |
| 107 | |
| 108 | e->type = KMEMCHECK_ERROR_INVALID_ACCESS; |
| 109 | |
| 110 | e->state = state; |
| 111 | e->address = address; |
| 112 | e->size = size; |
| 113 | |
| 114 | /* Save regs */ |
| 115 | memcpy(&e->regs, regs, sizeof(*regs)); |
| 116 | |
| 117 | /* Save stack trace */ |
| 118 | e->trace.nr_entries = 0; |
| 119 | e->trace.entries = e->trace_entries; |
| 120 | e->trace.max_entries = ARRAY_SIZE(e->trace_entries); |
| 121 | e->trace.skip = 0; |
| 122 | save_stack_trace_bp(&e->trace, regs->bp); |
| 123 | |
| 124 | /* Round address down to nearest 16 bytes */ |
| 125 | shadow_copy = kmemcheck_shadow_lookup(address |
| 126 | & ~(SHADOW_COPY_SIZE - 1)); |
| 127 | BUG_ON(!shadow_copy); |
| 128 | |
| 129 | memcpy(e->shadow_copy, shadow_copy, SHADOW_COPY_SIZE); |
| 130 | |
| 131 | kmemcheck_show_addr(address); |
| 132 | memory_copy = (void *) (address & ~(SHADOW_COPY_SIZE - 1)); |
| 133 | memcpy(e->memory_copy, memory_copy, SHADOW_COPY_SIZE); |
| 134 | kmemcheck_hide_addr(address); |
| 135 | |
| 136 | tasklet_hi_schedule_first(&kmemcheck_tasklet); |
| 137 | } |
| 138 | |
| 139 | /* |
| 140 | * Save the context of a kmemcheck bug. |
| 141 | */ |
| 142 | void kmemcheck_error_save_bug(struct pt_regs *regs) |
| 143 | { |
| 144 | struct kmemcheck_error *e; |
| 145 | |
| 146 | e = error_next_wr(); |
| 147 | if (!e) |
| 148 | return; |
| 149 | |
| 150 | e->type = KMEMCHECK_ERROR_BUG; |
| 151 | |
| 152 | memcpy(&e->regs, regs, sizeof(*regs)); |
| 153 | |
| 154 | e->trace.nr_entries = 0; |
| 155 | e->trace.entries = e->trace_entries; |
| 156 | e->trace.max_entries = ARRAY_SIZE(e->trace_entries); |
| 157 | e->trace.skip = 1; |
| 158 | save_stack_trace(&e->trace); |
| 159 | |
| 160 | tasklet_hi_schedule_first(&kmemcheck_tasklet); |
| 161 | } |
| 162 | |
| 163 | void kmemcheck_error_recall(void) |
| 164 | { |
| 165 | static const char *desc[] = { |
| 166 | [KMEMCHECK_SHADOW_UNALLOCATED] = "unallocated", |
| 167 | [KMEMCHECK_SHADOW_UNINITIALIZED] = "uninitialized", |
| 168 | [KMEMCHECK_SHADOW_INITIALIZED] = "initialized", |
| 169 | [KMEMCHECK_SHADOW_FREED] = "freed", |
| 170 | }; |
| 171 | |
| 172 | static const char short_desc[] = { |
| 173 | [KMEMCHECK_SHADOW_UNALLOCATED] = 'a', |
| 174 | [KMEMCHECK_SHADOW_UNINITIALIZED] = 'u', |
| 175 | [KMEMCHECK_SHADOW_INITIALIZED] = 'i', |
| 176 | [KMEMCHECK_SHADOW_FREED] = 'f', |
| 177 | }; |
| 178 | |
| 179 | struct kmemcheck_error *e; |
| 180 | unsigned int i; |
| 181 | |
| 182 | e = error_next_rd(); |
| 183 | if (!e) |
| 184 | return; |
| 185 | |
| 186 | switch (e->type) { |
| 187 | case KMEMCHECK_ERROR_INVALID_ACCESS: |
| 188 | printk(KERN_ERR "WARNING: kmemcheck: Caught %d-bit read " |
| 189 | "from %s memory (%p)\n", |
| 190 | 8 * e->size, e->state < ARRAY_SIZE(desc) ? |
| 191 | desc[e->state] : "(invalid shadow state)", |
| 192 | (void *) e->address); |
| 193 | |
| 194 | printk(KERN_INFO); |
| 195 | for (i = 0; i < SHADOW_COPY_SIZE; ++i) |
| 196 | printk("%02x", e->memory_copy[i]); |
| 197 | printk("\n"); |
| 198 | |
| 199 | printk(KERN_INFO); |
| 200 | for (i = 0; i < SHADOW_COPY_SIZE; ++i) { |
| 201 | if (e->shadow_copy[i] < ARRAY_SIZE(short_desc)) |
| 202 | printk(" %c", short_desc[e->shadow_copy[i]]); |
| 203 | else |
| 204 | printk(" ?"); |
| 205 | } |
| 206 | printk("\n"); |
| 207 | printk(KERN_INFO "%*c\n", 2 + 2 |
| 208 | * (int) (e->address & (SHADOW_COPY_SIZE - 1)), '^'); |
| 209 | break; |
| 210 | case KMEMCHECK_ERROR_BUG: |
| 211 | printk(KERN_EMERG "ERROR: kmemcheck: Fatal error\n"); |
| 212 | break; |
| 213 | } |
| 214 | |
| 215 | __show_regs(&e->regs, 1); |
| 216 | print_stack_trace(&e->trace, 0); |
| 217 | } |
| 218 | |
| 219 | static void do_wakeup(unsigned long data) |
| 220 | { |
| 221 | while (error_count > 0) |
| 222 | kmemcheck_error_recall(); |
| 223 | |
| 224 | if (error_missed_count > 0) { |
| 225 | printk(KERN_WARNING "kmemcheck: Lost %d error reports because " |
| 226 | "the queue was too small\n", error_missed_count); |
| 227 | error_missed_count = 0; |
| 228 | } |
| 229 | } |